Electron-damage studies in silicon at low temperatures

The defects introduced into high-purity n- and p-type Si specimens by electron irradiation of 0.8 to 1.5 MeV at low temperature (approximately 10 K) are monitored by bridge measurements of capacitance and loss factor of a capacitor formed by the evaporation of gold electrodes on opposite faces of a thin slab of the specimen. The results of measurements between 4.2 and 78 K or above are attributed in two different temperature regimes to (a) a silicon-dielectric capacitor with loss arising from an AC hopping conduction process by electrons between localised states at low temperatures and (b) two surface-barrier layer capacitors connected in series by band conduction in the bulk semiconductor at higher temperatures. At the transition temperature between the two regimes, the loss generally shows a large peak whilst the capacitance rises to the value determined by the barrier thicknesses. (author)